Abstract: A method includes firing a first burner into a furnace process chamber in a first initial condition, firing a second burner into the process chamber in a second initial condition, and measuring temperature at each of an array of locations in the process chamber. The first burner is adjusted to a first adjusted condition while the second burner is being fired at the second initial condition, and a resulting first temperature change is measured at each of the locations. The second burner is adjusted to a second adjusted condition while the first burner is being fired at the first initial condition, and a resulting second temperature change is measured at each of the locations. The measured first and second temperature changes are recorded as reference data for adjusting burner conditions to adjust temperatures at each of the locations. The method can thus be used to improve temperature uniformity throughout the array of locations.

Abstract: A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.

Abstract: A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.

Abstract: A furnace has a melting chamber with a periphery defined by a surrounding wall structure. The furnace is provided with a purge system configured to direct inert gas to flow downward in the melting chamber in the configuration of a curtain that adjoins the wall structure and reaches only partially around the periphery of the melting chamber.

Abstract: A method includes firing a first burner into a furnace process chamber in a first initial condition, firing a second burner into the process chamber in a second initial condition, and measuring temperature at each of an array of locations in the process chamber. The first burner is adjusted to a first adjusted condition while the second burner is being fired at the second initial condition, and a resulting first temperature change is measured at each of the locations. The second burner is adjusted to a second adjusted condition while the first burner is being fired at the first initial condition, and a resulting second temperature change is measured at each of the locations. The measured first and second temperature changes are recorded as reference data for adjusting burner conditions to adjust temperatures at each of the locations. The method can thus be used to improve temperature uniformity throughout the array of locations.

Abstract: A method heats a furnace process chamber with the combustion of fuel gas. The method heats the process chamber in a preheat mode when the temperature of the process chamber is below the autoignition temperature of the fuel gas. The preheat mode forms preheated combustion air by directing the combustion air through a regenerative bed. A stream of the preheated combustion air is directed into the process chamber in a condition unmixed with fuel gas. The preheat mode also forms a fuel rich mixture of the fuel gas and unheated combustion air. The fuel rich mixture is directed into the process chamber adjacent to the stream of preheated combustion air.

Abstract: An apparatus includes first and second mixer tubes. The first mixer tube contains a first gas flow passage having an inlet communicating with the source of fuel gas and an outlet to a combustion chamber. The second mixer tube contains a second gas flow passage having an inlet communicating with the source of combustion air and an outlet to the combustion chamber. The apparatus further includes premix control means for forming fuel gas-combustion air premix in the second passage by directing fuel gas from the first passage into the second passage, and for alternatively forming fuel gas-combustion air premix in the first passage by directing combustion air from the second passage into the first passage.

Abstract: An apparatus includes first and second mixer tubes. The first mixer tube contains a first gas flow passage having an inlet communicating with the source of fuel gas and an outlet to a combustion chamber. The second mixer tube contains a second gas flow passage having an inlet communicating with the source of combustion air and an outlet to the combustion chamber. The apparatus further includes premix control means for forming fuel gas-combustion air premix in the second passage by directing fuel gas from the first passage into the second passage, and for alternatively forming fuel gas-combustion air premix in the first passage by directing combustion air from the second passage into the first passage.

Abstract: An apparatus for use with a launder shell includes a heating component formed of refractory material. The heating component has a compartment configured to contain an electrical heating element. The apparatus further includes an elongated trough section configured for placement in an installed position inside the shell. The trough section has a fluid flow channel and a cavity beneath the channel. The cavity is configured to receive and support the heating component for movement into and out of the installed position together with the trough section.

Abstract: Air and fuel are directed from a burner outlet into a furnace process chamber in streams concentric on an axis, including an annular peripheral stream that includes fuel gas and adjoins products of combustion in the process chamber.

Abstract: A radiant heating panel has an inner side surface configured to face into a combustion chamber and an outer side surface configured to face oppositely away from the combustion chamber. The panel has interconnected sections formed of ceramic material. The panel sections are elongated with adjacent longitudinal edge portions, and are joined and sealed together along the adjacent longitudinal edge portions. The outer side surface of the panel has a contour that undulates laterally across the panel sections.

Abstract: A method directs fuel-oxidant premix into a reaction zone through a first total premix inlet flow area, and causes the premix to combust and form a stable flame projecting into a process chamber through an outlet from the reaction zone. At a time when the process chamber has a temperature at or above an auto-ignition temperature of the fuel, the flame is blown off to initiate diffuse combustion in the process chamber without a stable flame. The flame is blown off by directing the premix into the reaction zone through a second total premix inlet flow area greater than the first total premix inlet flow area.

Abstract: A method supplies reactants, including fuel gas, to burners that discharge the reactants into a furnace process chamber. In a stable flame mode of operation, stable flames are projected from the burners into the furnace process chamber. At a time when the furnace process chamber has a temperature at or above an autoignition temperature of the fuel gas, a diffuse combustion mode is initiated by supplying a selected burner with additional reactants, including reactants diverted from another burner, to blow off the stable flame at the selected burner.

Abstract: An apparatus for use with a launder shell includes a heating component formed of refractory material. The heating component has a compartment configured to contain an electrical heating element. The apparatus further includes an elongated trough section configured for placement in an installed position inside the shell. The trough section has a fluid flow channel and a cavity beneath the channel. The cavity is configured to receive and support the heating component for movement into and out of the installed position together with the trough section.

Abstract: A low NOx combustion method includes steps of injecting reactants into a combustion chamber. A primary reactant stream, including fuel and combustion air premix, is injected from a premix burner port into the combustion chamber. A staged fuel stream is injected into the combustion chamber from a staged fuel injector port adjacent to the premix burner port. A stream of recirculated flue gas is injected into the combustion chamber from a flue gas injector port that is adjacent to the premix burner port and adjacent to the staged fuel injector port. In this manner, the stream of recirculated flue gas is injected into the combustion chamber unmixed with the primary reactant stream and unmixed with the staged fuel stream.

Abstract: Air and fuel are directed from a burner outlet into a furnace process chamber in streams concentric on an axis, including an annular peripheral stream that includes fuel gas and adjoins products of combustion in the process chamber.

Abstract: A method directs fuel-oxidant premix into a reaction zone through a first total premix inlet flow area, and causes the premix to combust and form a stable flame projecting into a process chamber through an outlet from the reaction zone. At a time when the process chamber has a temperature at or above an auto-ignition temperature of the fuel, the flame is blown off to initiate diffuse combustion in the process chamber without a stable flame. The flame is blown off by directing the premix into the reaction zone through a second total premix inlet flow area greater than the first total premix inlet flow area.

Abstract: A steam generator has a heat exchange chamber with an upstream end and a downstream end. The steam generator further has a burner that injects primary reactants, including fuel and combustion air, into the chamber at the upstream end. A first branch of a once-through water line is located within the chamber downstream of the burner. A second branch of the once-through water line is connected in parallel with the first branch, and is located within the chamber downstream of the first branch. A fuel injector is arranged to inject staged fuel into the chamber at a staged location downstream of the first branch of the once-through water line.

Abstract: A method supplies reactants, including fuel gas, to burners that discharge the reactants into a furnace process chamber. In a stable flame mode of operation, stable flames are projected from the burners into the furnace process chamber. At a time when the furnace process chamber has a temperature at or above an autoignition temperature of the fuel gas, a diffuse combustion mode is initiated by supplying a selected burner with additional reactants, including reactants diverted from another burner, to blow off the stable flame at the selected burner.

Abstract: A method supplies reactants, including fuel gas, to burners that discharge the reactants into a furnace process chamber. In a stable flame mode of operation, stable flames are projected from the burners into the furnace process chamber. At a time when the furnace process chamber has a temperature at or above an autoignition temperature of the fuel gas, a diffuse combustion mode is initiated by supplying a selected burner with additional reactants, including reactants diverted from another burner, to blow off the stable flame at the selected burner.